青藏铁路遮阳棚路基试验工程效果实测研究

Engineering Effects of the Sunshine-shield Roadbed of the Qinghai-Tibet Railway in Permafrost Regions

太阳辐射是导致气温和地表温度升高的主要因素之一,遮挡了太阳直接辐射后可以有效降低地表温度.基于青藏铁路冻土区遮阳棚路基试验工程监测数据,分析了遮阳棚内外的气温差异和路基地温特征.结果表明:遮阳棚能够降低棚内气温,监测期间棚内年平均气温低于天然条件下平均气温值0.6℃;监测期内天然条件下近地表0.1～0.3m范围的气温高于1.0m以上气温近1℃,但在棚体内部仅相差约0.3℃;日最高气温值在棚体内外的单日差值达6.0℃,平均气温值在地面0.1m高度处相差4.2℃,1.5m高度处相差2.1℃;在遮阳棚的作用下,棚体内部及附近土体地温有所降低,且多年冻土上限有一定的抬升,抬升最大幅度达1.0m.监测结果显示了遮阳棚对于保护路基下冻土的良好效果.

The main factor causing rise of air temperature and ground temperature is solar radiation. To shield ground surface from solar radiation can effectively lower ground temperature. According to the field testing results of sunshine-shield roadbed in the Qinghai-Tibet Railway in permafrost regions,the mean annual air temperature （MAAT） inside the shield was 0.6 ℃ lower than that outside the shield during the monitored period. Under the original conditions,the MAAT within a height range from 0.1 to 0.3 m above ground surface was 1.0 ℃ higher than that of 1.0 m. However,the difference was only 0.3 ℃ inside the shield. The air temperature at 14：00 in a day during the warm season inside the shield was 6.0 ℃ lower than that outside the shield. The MAAT at 14：00 at 0.1 m height inside the shield was 4.2 ℃ lower than that outside the shield. And the difference at the height of 1.5 m was 2.1 ℃. Owing to the effect of the shield,the ground temperature under the shield decreased and the artificial permafrost table rose,with a maximum of 1.0 m. Both the air temperature and the ground temperature changes indicated that the sunshine-shield can effectively protect the underlying permafrost.